1. Field of the Invention
The present invention relates to a power unit for a motorcycle that includes an internal combustion engine provided with a crankcase rotatably supporting a crankshaft with an axis extending in the vehicle-width direction and a power transmission device for changing and reducing the speed of rotational power from the crankshaft and transmitting it to a rear wheel. In this power unit, an oil pump for supplying oil to the lubricating portions of the internal combustion engine is mounted on the crankcase and a balancer is rotatably supported by the crankcase. In addition, rotational power from the crankshaft is transmitted to a pump driven member provided on the pump shaft of the oil pump and to a balancer driven member coaxially interlinked with and connected to the balancer so as to transmit power to the balancer.
2. Description of Background Art
A power unit for a motorcycle is disclosed in the Japanese translation of PCT International Application No. 2003-085285 in which a balancer gear is provided on a balancer so as to receive rotational power transmitted from the crankshaft. A pump gear is provided on a pump shaft of the an oil pump so as to receive the rotational power transmitted from the crankshaft. The balancer gear and the pump gear are disposed to be vertically spaced apart from each other.
However, as shown in Japanese translation of PCT International Application No. 2003-085285, the configuration where the balancer gear and the pump gear are disposed to be spaced apart from each other causes the power unit to be bigger.